Process for manufacturing photosensitive module

ABSTRACT

A process for fabricating a semiconductor device is provided. The process integrates a cutting film process into the front-end of semiconductor process. The cutting film is directly formed on the curved surface of the micro-lens or a passivation layer is formed on the micro-lens before covering the passivation layer with the cutting film. In addition to micro-particle contamination due to sawing, the process is able to simplify chip packaging and reduce the size of a photosensitive module.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device. Moreparticularly, the present invention relates to a photosensitivesemiconductor device and manufacturing method thereof.

2. Description of the Related Art

Semiconductor fabrication is one of the fastest growing industry in theworld. Following the rapid progress of electronic technologies, morepersonalized and functionally powerful electronic products continue toappear in the market.

In the front-end of semiconductor process, at least five photomasks arerequired to pattern out the active regions, the gate structures, themetallic layers, the source/drain contacts, the metallic interconnectsand the bonding pad openings. To form a photosensitive device, anadditional masking step for patterning out an illumination area isrequired after an ion implantation for forming the source/drainterminals. Light energy received from the photo diode array onto theillumination area is converted into an electrical signal so that someimage data can be extracted. The most common photosensitive devicesinclude the charge-couple devices (CCD) and complementarymetal-oxide-semiconductor (CMOS) devices.

FIG. 1 is a schematic cross-sectional view showing the structure of aconventional photosensitive device. In the back-end of semiconductorprocess, modular semiconductor devices 100 (or chip) such as thephotosensitive device are singulated and packaged on a substrate such asa lead frame or other types of carrier 110. Thereafter, the package iselectrically connected with an external printed circuit board 120 orother external printed circuits such as a flexible printed circuit toform a photosensitive module or an image-sensing module. In addition,the larger the area of the patterned illumination area and the greaterthe number of photo diode array (not shown) within the illuminationarea, the higher will be the resolution of the photosensitive module.

It is to be noted that a lens 130 is incorporated into thephotosensitive module to increase light intensity after packaging thephotosensitive device. Moreover, an infrared cutting film 140 is alsoset between the lens and the photosensitive module for blocking out mostnon-visible light. The lens 130 and the infrared cutting film 140 arestationed using a holder 150. Hence, the assembled photosensitive deviceis quite bulky. Furthermore, during the back-end modularization process,micro-particles produced by cutting or contaminant particles emittedfrom packaging material may lower the yield of the photosensitivemodule. In addition, the lens 130 and the infrared cutting film 140 arenot packaged together in a single back-end process. Thus, efficiency ofthe packaging process is also compromised.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide asemiconductor manufacturing process for fabricating a photosensitivemodule that combines the process of fabricating an infrared cutting filmwith a front-end process. Ultimately, overall quality of aphotosensitive module is improved.

A second object of this invention is to provide a photosensitive modulethat simplifies the packaging process and reduces overall volume of thephotosensitive module.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, theinvention provides a semiconductor manufacturing process. First, a waferhaving at least an active device and an array of photo diode array on anactive layer over the wafer is provided. Furthermore, the surface of thewafer furthermore has a metallic interconnect layer for connecting theactive devices and the gate terminal of the array of photo diode array.In addition, the surface of the wafer has an illumination area locatedabove the photo diode array. Thereafter, at least a micro-lens is formedover the illumination area of the wafer. Finally, a cutting layer isformed over the micro-lens.

This invention also provides a photosensitive module. The photosensitivemodule comprises a substrate, an active layer, a metallic interconnectlayer, at least a micro-lens and a cutting film. The active layer is setover the substrate. The active layer at least has an active device and aphoto diode array. The photo diode array and the active device areelectrically connected via the metallic interconnect layer. Themicro-lens is set on the surface of the outermost metallic interconnectlayer above the photo diode array. The cutting film is set over themicro-lens.

According to one embodiment of this invention, the micro-lens and thecutting film are fabricated together in a single step. Thereafter, amodularization process that includes separating the photosensitivedevices and attaching each photosensitive device to a substrate such asa lead frame or other type of carrier to form a photosensitive module oran image-sensing module.

At the end of the chip fabrication process, a low-temperature magneticsputtering machine can be deployed to deposit a layer of silicon dioxideover the chip. The silicon dioxide layer may serve as a protective layeror plastic material layer. Thereafter, an infrared cutting film iscoated over the protective silicon dioxide layer. Finally, thechip-on-film (COF) technique is deployed to package the chip so thatsome packaging time is saved and micro-particle contamination isprevented.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic cross-sectional view showing the structure of aconventional photosensitive device.

FIGS. 2A through 2D are schematic cross-sectional views showing theprogression of steps for producing a semiconductor device according toone preferred embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

FIGS. 2A through 2D are schematic cross-sectional views showing theprogression of steps for producing a semiconductor device according toone preferred embodiment of this invention. As shown in FIG. 2A, a wafer200 is provided. The wafer 200 has at least an active device 212 and anarray of photo diode array 214 formed on an active layer 210 byperforming a series of masking steps. The active device 212 is ametal-oxide-semiconductor (MOS) transistor such as a PMOS or CMOStransistor, for example. The PMOS transistor is normally formed on theupper surface of an N-well 202 within the silicon substrate (the wafer)200. The photo diode array 214 is formed on the upper surface of aP-well 204 within the silicon substrate 200. Thereafter, a gate oxidelayer 206 is formed over the silicon substrate 200 to isolate the activedevice 212 from the photo diode array 214. A second masking step is nextcarried out to form the contact opening for the gate (the source and thedrain) of the active device 212 and the photo diode array 214.Conductive material is deposited into the opening to form electricalconnection with the metallic interconnect layer 220 by sputteringaluminum alloy. A dielectric material having good insulating propertiessuch as silicon dioxide is disposed between the first metallic layer 222and the second metallic layer 226 of the metallic interconnect layer 220to prevent short-circuit. Another masking step is performed to patternout the contact openings on the outermost surface of the metallicinterconnect layer 220 for forming the bonding pads 228. Up to thispoint, all the front-end processing steps for fabricating an integratedcircuit is almost complete.

Afterwards, another masking step is performed to pattern out anillumination area 230 located above the photo diode array 214. When thephoto diode array 214 is illuminated by an external visible lightsource, the photo diode array 214 is able to detect the light andconvert photonic energy into electrical signals. The electrical signalsare transmitted to other devices via the active device 212 and themetallic interconnects 220. Thereafter, a micro-lens 240 or a micro-lensarray is formed over the illumination area 230 above the photo diodearray 214 to focus any incoming light. A high molecular weight polymermaterial is used to fabricate the micro-lens 240. The curved surface ofthe micro-lens 240 is self-created due to the high intrinsic surfacetension of the material. Hence, the cost for producing the micro-lens240 is low. Because the aforementioned steps can be carried out insequence instead of having to perform a modularization operation beforecarrying out a lens assembly and infrared cutting film fabricationprocess, both packaging time and cost are reduced.

As shown in FIG. 2B, a cutting film 244 is formed over the micro-lens240. The cutting film 244 is a layer for blocking out infrared or farinfrared light but permits the passage of visible light into the photodiode array 214. In this embodiment, a passivation layer 242 is alsoformed between the cutting film 244 and the micro-lens 240. Thepassivation layer 242 is comprised of a silicon dioxide layer and may beformed, for example, by performing a low-temperature sputtering processand then planarizing the layer in a chemical-mechanical polishing (CMP)operation. The cutting film 244 is formed over the planarizedpassivation layer 242, for example, by coating or sputtering. However, amaterial constituting the cutting film 244 may be directly depositedover the curved surface of the micro-lens 240 by sputtering, forexample.

As shown in FIGS. 2C and 2D, the cutting film 244 is patterned usingphotolithographic and etching processes to form openings 246 that exposethe respective bonding pads 228. Since the cutting film 244 and themicro-lens 240 have already been fabricated within the front-end ofsemiconductor process, the devices can be singulated to form individualchips 200 a. Afterwards, the chip 200 a is modularized by bonding thechip 200 a to a substrate, a lead frame or other type of carrier (notshown). Alternatively, the bonding pads 228 of the chip 200 a areelectrically connected to a flexible carrier 250 via an anisotropicconductive plastic 248 to form a chip-on-film (COF) light sensor asshown in FIG. 2D.

In summary, major advantages of the semiconductor manufacturing processaccording to this invention includes:

1. The steps for forming the micro-lens and the cutting film of thephotosensitive device are performed before modularizing the chip byperforming singulation and packaging processes. Hence, processing timeand cost are saved and contamination of the device by micro-particlesreleased from the cutting process is prevented.

2. The fabrication of the cutting film is in the front-end semiconductorprocess. Moreover, the cutting film may be directly formed over thecurved surface of the micro-lens or after forming a passivation layerover the micro-lens. Ultimately, volume occupation of the photosensitivemodule can be reduced and yield of the photosensitive module can beincreased.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A process for manufacturing a semiconductor device, comprising thesteps of: providing a wafer having at least an active device and a photodiode array, wherein the wafer has a metallic interconnect layer thatelectrically connects with the active device and the photo diode array,the metallic interconnect layer has a plurality of bonding pads locatedon the surface of the outermost metallic interconnect layer, and thewafer has an illumination area located above the photo diode array;forming at least a micro-lens over the illumination area of the wafer;and forming a cutting film over the micro-lens, wherein the cutting filmis directly formed on the curve surface of the micro-lens.
 2. Theprocess of claim 1, wherein alter the step of forming the cutting film,further comprises a step of patterning the cutting film to form aplurality of openings that exposes the respective bonding pads.
 3. Theprocess of claim 1, wherein alter the step of forming the cutting film,further comprises a step of singulating the chips within the wafer.
 4. Aprocess for manufacturing a semiconductor device, comprising the stepsof: providing a wafer having at least an active device and a photo diodearray, wherein the wafer has a metallic interconnect layer thatelectrically connects with the active device and the photo diode array,the metallic interconnect layer has a plurality of bonding pads locatedon the surface of the outermost metallic interconnect layer, and thewafer has an illumination area located above the photo diode array,forming at least a micro-lens over the illumination area of the wafer;and forming a cutting film over the micro-lens, wherein before the stepof forming the cutting film, further comprises a step of forming apassivation layer over the micro-lens so that the cutting film is formedover the passivation layer instead of directly forming over themicro-lens.
 5. The process of claim 4, wherein after the step of formingthe cutting film, further comprises a step of patterning the cuttingfilm to form a plurality of openings that exposes the respective bondingpads.
 6. The process of claim 4, wherein after the step of forming thecutting film, further comprises a step of singulating the chips withinthe wafer.